Many forms of automotive sport are popular in both amateur and professional circles using four wheeled vehicles. Operators compete and test their skills in speed and maneuverability. With advances in technology, the speed capabilities of vehicles used in competition has steadily increased. The risk of accidental injury involving high speed and possibly an interaction with a vehicle having substantial momentum call for the use of suitable and effective safety equipment. The risk of head and cervical spine injuries is of particular concern because of the severe and permanent nature of many head and spine injuries.
The use of protective head gear was adopted as standard practice, early in the history of motor sports. A helmet with a padded interior and a hard shell exterior is the current protective head gear of choice. The Safety Foundation Institute has been formed to set safety standards for equipment and to test equipment for certification. Standards have been set to provide a reasonable level of safety in view of the typical speed at which particular equipment will be used.
In addition to safety helmets, vehicles having a chassis are frequently equipped with a roll support structure to support the vehicle or resist the force of impact, in the event of a roll over or collision with another vehicle. Roll bars and roll cages are typical roll support structures. These structures are permanently attached to the vehicle and are designed to support the vehicle or resist the force of impact to avoid having the body of the occupant receive the force. Roll support structures are designed using physics and geometry to produce a structure of maximum strength. The vehicle body typically protects the lower body of the occupant, while the vehicle is being operated; however, the upper body is typically exposed above the chassis and other impact resistant parts of the vehicle. The roll support structure is typically installed proximate to the upper body of the occupant to protect the upper torso and head; the head and cervical spine are the most vulnerable to accidents. In order to support the weight of the vehicle and to resist collision impact, the roll support structure is typically comprised of rigid and hard members, such as steel or steel alloy, which can cause injury if the occupant contacts these members with an appreciable degree of speed. It is desirable to apply padding to the roll support structure members to reduce the potential for injury to the head and cervical spine. Head and spine injuries occur because of impact with roll bars and roll cages, at high speeds, even when approved protective helmets are being worn.
The Safety Foundation Institute has set standards for all safety equipment used in sanctioned motor sport events, including the padding applied to roll support structures. Safety Foundation Institute (SFI) standards have been adopted by Formula 1 Racing, NASCAR, BUSH, IRL, NHRA, IHRA, and SCCA. The Safety Foundation Institute has used the GADD severity index as a parameter in setting the standard for roll support structure padding. It is desirable that roll support structure padding have compressible and resilient properties as well as acceptable fire resistant properties. The initial standard required that the padding allow no greater force than that comparable to 200 times gravitational force be applied to the head or any limb coming into contact with the padding at any time during a standard “G” test. The padding material had to withstand a temperature of 1450 degrees Fahrenheit for at least 15 seconds without melting or dripping. Original standards required that the padding must establish a GADD severity index no higher than 1500. The GADD severity index was developed at Wayne State University Head Trauma Center and consists of an algorithm used to process test data to produce the index value. Subsequent data relating to head and cervical spine injuries highlighted the danger of severe injury from impact and the Safety Foundation Institute altered the roll support structure padding standard to require a GADD severity index of no higher than 1250.
In order to meet these rigid standards, all SFI approved roll support structure padding materials are relatively dense to prevent collapsing; consequently, the padding stops the movement of the occupant's head relatively quickly. The time interval during which the occupant's head is in contact with the padding and is decelerating, is termed “spike time” and typically falls within the range of two to four milliseconds. Dense padding materials have caused helmets, being worn by occupants, to crack on impact with the padding. Rapid deceleration of the head contributes to head and spine injuries. A relatively short spike time delivers a greater mechanical impulse to the head, contributing to more severe head injuries. A relatively short spike time indicates that the head stops more quickly while the upper torso continues to travel, causing the cervical spine to over extend, thus contributing to more severe spine injuries. At present, all SFI approved padding materials are dense and cannot be deformed by manual pressure. A more readily compressible material having a longer spike time is desirable. A longer spike time reduces the force applied to the head during each increment during the time interval, reducing the mechanical impulse delivered to the head and reducing extension of the cervical spine.
There is a need for a roll support structure padding which incorporates the compressible and resilient properties necessary to meet the GADD index standard and the “G” test, with temperature resistant properties necessary to meet the heat resistant standard in a padding material which can be readily molded, cut, and installed on roll support structures. There is a need for a roll support structure padding which is readily compressible and resilient so as to significantly lengthen the spike time duration and provide increased and adequate protection against head and cervical spine injuries.